Method of removing thiophenols from phenols



April 16, 1957 METHOD OF' REMOVING THIOPHENOLS FROM PHENOLS M. B.NEUWORTH Filed Aug. lO, 1954 2 Sheets-Sheet 1 46 noue-aus I6 Aaa/foussal. VENT soLvE/vr 'un-u xr J r4s "-59 1 lo ,4 ze -aa u 'u 'll t k e z sE h g E 24 t 4l k z L-p u. n 2 g l2 h q E k 5 0 Q "I k g t a e 1 Je 01"-"1 az sz 2s naar/mums pendre l l "o 5| pHEnoLs lun/T114 INVENTOR.F/GURE MART/NBNEUWORTH April 16, 1957 M. B'NEUWORTH 2,789,145

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MAR' Tl/v NEI/WORTH m7 kuk A TTR/VEY United States Patent O METHOD 0FREMGVING THIOPHENOLS FROM PHENLS Martin B. Neuworth, Pittsburgh, Pa.,assigner to Pittsburgh Consolidation Coal Company, Pittsburgh, Pa., acorporation of Pennsylvania Application August 10, 1954, Serial No.448,947

9 Claims. (Cl. 269-627) This invention relates to the art of refiningphenols, and more particularly, to the removal of thiophenols fromphenols.

The two principal commercial sources of phenols are coke oven tar andpetroleum distillates resulting from oil cracking processes. Theconventional method of recovering phenols from either source is toextract them with aqueous caustic solution to produce Water solublephenolate salts. The latter are separated from the source material bydecantation and reconverted to phenols upon reaction with mineral acids.Other sources of phenols include tar from low temperature coalcarbonization and oil shale distillates. The term phenols encompassesthose hydroxy aromatic compounds, principally the mononuclear compounds,but also including the polynuclear compounds, for example, phenolitself, cresols, xylenols, higher methyl substituted phenols, ethylphenols and higher alkylated phenols, bicyclic, polycyclic and dihydricphenols. The fraction of phenols boiling below 230 C. includes most ofthe commercially valuable phenols, i. e., phenol itself, cresols,xylenols and ethyl phenols.

Extraction of phenols by means of aqueous caustic solution isaccompanied by the extraction of thiophenols since the latter are evenstronger acids than the phenols themselves. The quantity of thiophenolsin the Original source material varies widely, being sometimes as littleas one percent by Weight of the phenols and ranging as high as 25percent and above. Their presence in the eX- tracted phenols isundesirable for most industrial applications.

Many schemes have been proposed for the removal of the thiophenols fromthe caustic extracted phenols. The successful ones are based upon theease of oxidation of the thiophenols to disuldes. lt is diicult to keepthiophenols free of disuides since normal handling will expose them toair and result in at least partial oxidation. Accordingly the proposedschemes, in View of this behavior, have resorted to deliberate oxidationby air blowing to completely convert the thiophenols to disuldes. Thelatter are readily separable from the phenols because of theirinsolubility in an aqueous medium.

The general method of oxidizing thiophenols to disuldes has threedisadvantages; Firstly, destruction of a signicant quantity of thevaluable phenols results from the oxidation; secondly, redistillation ofthe phenols causes a reversion of any remaining disulli'des tothiophenols; 4there thirdly, the thiophenol content of the resultingphenols is still not reduced suiciently for some commercialapplications.

Analysis of a typical commercial product of petroleum cresylics (i. e.phenols boiling below 230 C.) that were recovered by caustic extractionand oxidized to remove thiophenols shows 97.7% by weight of phenols; 1%by weight of neutral oil; 1% by weight of sulfur compounds (total); and0.3% by weight of tar bases. The sulfur is, of course, present inorganic sulfur compounds, principally unoxidized or reconvertedthiophenols, and disuldes resulting from oxidation of the thiophenols.

2,789,145 Patented Apr. 1.6, 1957 2 For many industrial resinapplications, 1% by weight of sulfur compounds is too high.

ln accordance with the present invention, I have provided a method forremoving thiophenols from phenols which are substantially free of.neutral oil. The method comprises contacting the contaminated phenols ina continuous, countercurre'nt' extraction zone with a low boilingparainic naphtha fraction as one vsolvent and an aqueous solution of anoxygenated hydrocarbon as the other solvent. The oxygenated hydrocarbonsused in the present invention are glycols, polyglycols and their methyland ethyl ethers.

When one contacts a mixture of phenols and thiophenols with a polar anda nonpolar solvent, one would expect the more strongly acidic thiophenolto remain lin the polar solvent (aqueous solutions of oxygenatedhydrocarbons) However, I have found that the reverse is true. The lessacidic phenols remain in the polar solvent (aqueous oxygenatedhydrocarbons) and the. more acidic thiophenols are recovered in thenonpolar solventy (low boiling parainic naphtha). The separationresulting from the present extraction treatment is extremely effective;phenols of high purity can be recovered in virtually quantitativeyields.

In the process of my invention, the feedstock consists of phenols fromwhich substantially all the neutral oil has been separated. Theetliciency of separating sulfur' compounds from phenols decreases asthe; neutral oil content ot' the mixture increases. ln general, theneutral oil contamination of the feed material should be'lessthan aboutl0 percent, preferably less than about 5 percent. This feed stockgenerally but not necessarily has a boiling range from 160-300D C., orsome portion thereof, particularly the fraction boiling upto 230 C. Theorganic sulfur contaminants comprising principally thiophenols (i. e.thiophenol itself, thiocresols, thioxylenols, etc.) may be present inamounts from about 0.5 to 25% by weight of the feedstock. The presentprocess iseiective in removing thiophenols from phenols and also eectivein eliminatingV the more readily separated' sulfur compounds, such asdisuldes. Thus the present process can be applied to fresh phenolsaswell as those which have been subjected to airblowing for partialoxidation of the thiophenols.

The contaminated feed stock is fed into a continuous, countercurrent,double'solvlent, extraction zone. Aqueous oxygenated hydrocarbonsolution is fed into one end of the zone, anda low boiling,essentiallyparatinic naphtha fraction is fed into the other end" of the'Zone. The aqueous solvent passes through the extraction zone dissolvingsubstantially all the phenols. The naphtha passes countercurrentlythrough the Zone dissolving the thiophenols and any residual neutraloil. The phenolsv then may be recovered readily from the aqueous solventby distillation, provided the boiling: ranges of the phenols and solventare dilerent. Similarly, the thiophenols may be recovered from thenaphtha solution for disposal as waste or for commercial use dependingupon thev quantity.

The oxygenated hydrocarbon materials which I` have found to be effectivein the present invention are glycols, polyglycols, and their methyl andethyl ethers. These compounds may be represented by the followingformula:

MOCEZIRONH Where R is H, CHs'or C21-I5; R' is H or CH3; and n is aninteger from l to 10 inclusive. It is necessary that theseoxygenated'hydrocarbon materials be used in an aqueous solutioncontaining from about 50/ to 80% by Weight of the oxygenatedhydrocarbons. In concentrations lbelow about 50 percent by weight ofoxygenate'd hydrocarbons, recovery of phenols is too low to bepractical. Above about 8O percent concentration of oxygenatedhydrocarbons, the aqueous solvent dissolves the thiophenols so that theextracted phenols remain contaminated to an undesirable extent.

Suitable .materials for the aqueous solvent include 4ethylene glycol,propylene glycol, monomethyl and monoethyl ethers of ethylene glycol,diethylene glycol, dipropylene glycol, monomethyl and monoethyl ether-sof diethyl- The processY of this invention is further criticallyconditioned by the characteristics of the naphtha solvent. lt "must lbeessentially paraflinic in character. may 'be obtained from thedistillation of parainic petro- Such solvents leum stock. VIts boilingrange should Ibe 60l30 C. but

preferably 60l00 C. in order -to facilitate the subse- Q quent strippingof the naphtha solvent from the naphtha y extract. And finally, thenaphtha density should be less th-an 0.80 and preferably less than 0.75to insure a grav- 'ity difference between the two phases in theextraction column suiiicient to Veffect a ready separation of thephases. The hexane cut of parainic naphtha combines all these criticalproperties and accordingly is preferred as the nonpolar solvent.

For a clear understanding of my invention, its objects and advantages,reference should Ibe had to the following description and accompanyingdrawings in which:

Figure l is a diagrammatic illustration of apparatus adapted for thepractice of the preferred embodiment of this invention; and

Figure 2 is a diagrammatic illustration of an alternate embodiment ofthis invention.

Referring to Figure l, a feedstock comprising phenols contaminated withsulfur compounds as previously devfined, is pumped continuously from astorage tank 10 through a pipeline 12 into a continuous countercurrent,

ldouble solvent extractionV zone consisting, in the preferredembodiment, of `a multistage, vertical, center feed extraction column14. The extraction column may be of any convenient design capable ofproviding a sucient number of theoretical extraction stages to effectthe desired separation of phenols. A conventional packed tower may beused, as well as a pierced plate column, a ybubble plate column, or acolumn containing alternate zones of quiescence and turbulence.

A polar aqueous solvent, as previously defined, is fed continuously froman aqueous solvent storage tank i6 through pipeline 18 into the top ofthe extraction column 14. Naphtha is fed continuously from the naphthastorage tank 20 through a pipeline 22 into the base of the extractioncolumn 14. Since the density of the aqueous solvent exceeds the densityof the naphtha, the aqueous solvent descends through the column,dissolving phenols While the lighter naphtha passed countercurrentlyupward through the column, dissolving the thiophenols contained in thefeed. Column throughput and contact time lare dependent upon columndesign.

For every volume of feedstock, from 0.5 to 5.0 volumes of vaqueoussolvent and from 0.5 to 5.0 volumes of naphtha should be employed, wherelboth high phenol recov- 1 ery and high phenol purity are desired. Theseflow ratios yare therefore preferred. While either of the two solventsmay be employed as the continuous phase in the extrac- Vindependent ofthe temperature at which the column is operated, it is preferred tooperate `the extraction column within the range of 60-120" F. Theincreased viscosity of the phenol feedstocks below this range introducescolumn operation difficulties, while the increasing solubility of thethiophenols in the aqueous solvent at higher temperatures decreases thepurity of the recovered phenols. It' necessary, the extraction columnmay be heated `or cooled in any convenient manner. Y

The aqueous solvent, containing purified phenols, is withdrawncontinuously from the lbottom of the extraction column 14 through `apipeline 24 and fed into a stripping column 26 for the separation of theaqueous solvent from the recovered puried phenols. Where the aqueoussolvent contains oxygenated hydrocarbons having a boiling range belowthat -of the recovered phenols, the oxygenated hydrocarbons will passoverhead through a conduit 38, a condenser 40 and a conduit 42 to theaqueous solvent tank 16 for recirculation in lthe process. A portion ofthe condensed distillate may Ibe returned to the column 26 as reuxthrough -conduit 44. The water entering the stripping column 26 alsowill pass overhead with the oxygenated hydrocarbon solvent. Puritiedphenols are recovered vat the bottom of the `stripping column 26 througha conduit 28 and a condenser 32. Any water remaining with the purifiedphenols is separated in a decanter 30 and returned for recirculation assolvent through conduit 36. Purified phenols essentially free ofthiophenols are recovered from the decanter 30 through conduit 34. Freshoxygenated hydrocarbon solvent may lbe added as makeup through conduit46.

Naphtha with dissolved thiophenols and any residual neutral oil leavesthe top of the extraction column 14 through pipeline 48 and passes to astripping column 50 where the naphtha is separated from the thiophenols.Naphtha passes overhead from the stripper 50 through a pipeline 52 andredux condenser 54. A portion of the condensed naphtha may berecirculated rthrough pipeline 56 as reflux for the stripper 50. Theremainder of the naphtha is returned to the naphtha storage tank 20through pipeline 58 for recirculation. Thiophenols leave the column 50as a `bott-om product through pipeline 60. A cooler 62 may be insertedin the exit pipeline 60 to cool the sulfur containing product.

Where the oxygenated hydrocarbon solvent of this invention has a boilingrange higher than that of the phenols being treated, the process shouldbe conducted in accordance with Figure 2. Referring to Figure 2, afeedstock containing phenols and sulfur compounds is introduced from astorage tank 70 through a conduit 72 into a countercurrent extractioncolumn 74. An aqueous solution of an oxygenated hydrocarbon material isintroduced .into the top of the column 74 lfrom a solvent tank 76through a conduit 78. A low boiling parat-linie naphtha Vsolvent fromstorage tank S0 is introduced through couduit 82 into the bottom of theextraction column 74. The aqueous solvent passes downwardly through thecolumn dissolving the phenols contained in the feed material. Theparaiiinic naphtha solvent passes upwardly through the column dissolvingthiophenols and any residual neutral oils which may exist in the feed.The naphtha extract is recovered from the top of the column 74 throughconduit 88 and sent to a naphtha stripping column 90. ln the naphthastripper 90 the low boiling solvent i-s vapor- 'ized and recoveredthrough conduit 92, condensed in a reflux condenser 94 and returnedthrough conduit 98 to the naphtha storage vessel 30. A portion of `thecon- -densed naphtha may be returned to the stripper 99 through theconduit-96 as reflux. Thiophenols are recovered from the strippingcolumn 90 through a conduit 100. If desired a cooling condenser 102 maybe provided in the withdrawal conduit.

The high boiling aqueous solvent extract is recovered from the bottom ofthe extraction column 74 through a conduit 84 and sent to a phenolstripping column` 86. Phenols and water pass from the top of thestripper 86 'through a condi1it1104 to areiux condenser 106. CondensedWater andl phenols are sent to a decanter 108 through a conduit 110. Aportion of the condensed water and ph'enolsrnay'be returned to the topof the stripping column 86 through a conduit 112 as redux. Purifiedphenols are recovered from the decanter 108 through a 6 Theyincluded.(l) ethylene glycol-monomethyl ether; (2) ethyleneY glycolmonoethylether; (3) ethylene glycol; (14) triethylene glycol; (5)polyprcpyleneglycol 150; and (-6) polyethylene glycol'600. Theconcentration of the aqueous solvent was from 70 to 80% by weight of theoxygenated hydrocarbon material.

The conditions and results 0f these runs are reported in the followingTable I.

Table I.-Remooal of thophenols a/nd dtsulfldes from phenols usi/ng assolvents hewane and aqueous solutions of oygenated hydro,cttrfbcmsVEthylene G1. co1 Ethylene Triethyl- Dipropyl# Polyethyl- Mgn GlycolEthylene ene Glycol ene ene Glycol Aqueous SolventComponeut meth 1 Mono-Glycol Glycol 1' 600 2 Ethel', ethyl Ether Boiling Temperature, D C 124.5 195 197 287 232V 40l) R CH3 (13H5 H H H H R'- H H H H CHI CHI 15.-.- 11 1 2 8-10 Aqueous Solvent Conc. (Wt. perce1! 70 80 75 70 70 70 FeedRates (Volumes): v

1 1 1 1 1 1 2 3 2 2 2 2 3 4 3 3 3 3 Recovery of Phenols iu Extract Y(W't. percent) 98. 0 95. 3 93. 8 99. 5 95. S 95. 4 Contaminants inRecovered Phenols (Wt. percent):

Thiopheuols 0. 07 0. 07 O. 007 0. 14 0. 04 0. 2 Disulfides 0. 13 0.060.023 0. 10 l). 08 0. 03

1 The dipropylenc glycol in this run -w'as a commercially availablesolvent sold under the name Polypropylena 150, consisting of a narrowboiling fraction o propylene glycol having an average molecular weight oabout 150. It is marketed by the Carbon and Carbide ChemicalsCorporation.

Polyethylene glycol 600 is a commercially available solvent consistingof a narrow boiling distillate of polyethylene glycol having an averagemolecular weight of about 600. It is marketed under the trade name"Carbowar by the Carbon and Carbide Chemicals Corporation.

withdrawal conduit 114. The water inthe decanter S is separated from thephenols and returned for recirculation to the aqueous solvent storagevessel 76 through a conduit 116.

The high boiling oxygenated hydrocarbon material used in the aqueoussolvent iswithdrawn from the bottom of the stripping column 36 through aconduit 11S and a cooling condenser 120. High boiling oxygenatedhydrocarbon material is returned to the aqueous solvent storage vessel76 for recirculation in the system. Additional high boilingoxygenated-hydrocarbon material may be introduced to the system asmakeup through a conduit 120.

Asrriention'ed previously, the system shown in Figure 2 is employed whenthe oxygenated hydrocarbon material has a higher. boiling range than thephenols being separated. The advantage o'f the use of a high boilingoxygenated hydrocarbon material is that the large quantities of solventrequired need not be vaporized prior to reuse in the process. In thepractice of the present invention according to Figure 2 only theproduct' purified phenols and water from the aqueous solvent need bevaporized to effect recovery of the phenols.

By yva'y of example, a series of runs will now be described 'which vwereconducted on a `commercially available product consisting of petroleumcresylics, i. e., phenols, having a boiling range of 375 to 450 F. Thepetroleum cresylics employed as the feed material contained thefollowing contaminants; thiophenol 0.6%, disuldes 4.0%, and neutral oil1.0%. The elemental sulfur in the feed material was 1.4% by weight.

The runs were conducted in a 1-inch diameter, 8-feet long, center feed,countercurrent extraction column containing in its contact zone 29settling stages alternately disposed with 28 agitation stages. Thecolumn was operated at a temperature of C. The continuous solvent. phasewas commercial grade hexane which was employed asv the nonpolar solvent.

Six different oxygenated hydrocarbons having the following formula:

moorden/OH where R is H, CH3 or CzHsg. R is H or CH3; and n is aninteger from l to v10 inclusive, were employed as the primary componentof the vaqueous polar solvent.

In the runs recorded in Table I recovery of phenols ranged from93.8-99.5%. The thiophenol contamination was reduced from its initialvalue of 0.6 weight percent to a value ranging from 0.007-0.l4 weightpercent. The disulfide content was reduced from its initial value of4.0% to a value in the range of 0.0234113 weight percent. Accordingly,even if the phenols containing thiophenOls are subjected toa preliminaryair blowing treatment, the resulting disulfides can be substantiallyeliminated by the present process.

To facilitate separation of the recovered phenols from the solvents, itis preferred that the oxygenated hydrocarbon used in the polar solventhave aboiling range outside that of the phenols in the feedstock. Thuspreferred solvents of the examples in Table I would include ethyleneglycol monorne'thyl ether as boiling below the range of the cresylics,and triethylene glycol, polypropylene glycol and polyethylene glycol6002s boiling above the range of the cresylics. The use of the other twoexamples, ethylene glycol monoethyl ether and ethylene glycol isWellsuited for eectng the desired elimination ofthe sulfur compoundsfrom the phenols, but it results in an extract which is not readilyseparable from the puried phenols by distillation.

And now according to the provisions of the patent statutes, I haveexplained the principle, preferred construction, and mode of operationof my invention and have illustrated and described what I now considerto represent its best embodiment. However, I desire to have itunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically illustrated anddescribed.

1 claim:

1. A method of separating thiophenols from a mixture of phenols andthiophenols that is substantially free of neutral oils which comprisesthe steps of feedingl said mixture of phenols to an extractionV zone,feeding to one end of said extraction zone an aqueous solutioncontaining from about 50 to about 80 percent by weight of an oxygenatedhydrocarbon having the formula where -R is a radical selected from theclass consisting-of H, 'CH3 and CzHs; R' is a radical selected from theclass consisting of H and CH3; and n is an integer having a value in therange of 1 to 10, feeding a parainic naphtha fraction boiling in therange of 60 to 130 C. and having a density of less than 0.8 to the otherend of said extraction zone, passing said aqueous solution and saidnaphtha fraction through said extraction zone in countercurrentrelation, and recovering the phenols principally in the aqueous solutionand the thiophenols principally in the naphtha fraction. v v Y 2. Amethod Vof separating thiophenols from a mixture of phenols Vandthiophenols that is substantially free of neutral oils which comprisesthe steps of feeding said mixture of phenols to a vertical extractionzone at a point located between the ends thereof, feeding to the upperend of said vertical extraction zone-an aqueous solution containing fromabout 50 to about 80 percent by Weight of an oxygenated hydrocarbonhaving the formula where R is a radical selected from the classconsisting of H, CH3 and CzHs; R is a radical selected from the `classconsisting of H and CH3; and n is an integer having a value in the rangeof l tol 10, feeding a paraiinic naphtha fraction boiling in the rangeof 60 to 130 C. and having a density of less than 0.8 to the bottom ofsaid extraction zone, passing said aqueous solution and said naphthafraction through said extraction zone in countercurrent relation, andrecovering the phenols principally in the aqueous solution and thethiophenols principally in the naphtha fraction.

3. A method of separating thiophenols from a phenol distillate fractionboiling within the range 170 to 230 C. comprising phenols andthiophenols and being substantially free of neutral oils, comprising thesteps of feeding said distillate fraction to a vertical extraction zoneat a point located between the ends thereof, feeding to the upper end ofsaid vertical extraction zone an aqueous solution containing from about50 to about 80 percent by weight of an oxygenated hydrocarbon boilingbelow 170 C. and having the formula where R is a radical selected fromthe class consisting of H, CH3 and CzHs; R' is a radical selected fromthe class consisting of H and CH3; and n is an integer having a value inthe range of l to 10, feeding to the bottom of said extraction zone aparaflnic naphtha fraction boiling in the range of 60 to 130 C. andhaving a density of less than 0.8, passing said aqueous solution andsaid naphtha fraction through said extraction zone in countercurrentrelation, and recovering the phenols principally in the aqueous solutionand the thiophenols principally in the naphtha fraction.

4. A method of separating thiophenols from a phenol distillate boilingwithin the range of 170 to 230 C. Comprising phenols and thiophenols andbeing substantially free of neutral oils, comprising the steps offeeding said distillate fraction to a vertical extraction zone at apoint located between the ends thereof, feeding to the upper end of saidvertical extraction zone an aqueous solution containing from about 50 toabout 80 percent by weight of an oxygenated hydrocarbon boiling above230 C. and having the formula where VR is a radical selected from theclass consisting of H, CH3 and CzHs; R is a radical selected from theclass consisting of H and CH3; and n is an integer having a value in therange of l to 10, feeding to the bottom of said extraction zone aparainic naphtha fraction boiling in the range of 60 to 130 C. andhaving a density of less than 0.8, passing said aqueous solution andsaid naphtha fraction through said extraction zone in counter- Y currentrelation, and recovering the phenols principally in the aqueous solutionand the thiophenols principally in the naphtha fraction. Y

5. A method of separating thiophenols Vfrom a mixture of phenols andthiophenols that is substantially free of neutral oils which comprisesthe steps of feeding said mixture of phenols to an extraction zone,feeding to one end of said extraction zone an aqueous solutioncontaining from about 50 to about 80 percent by Weight of ethyleneglycol monomethyl ether, feeding to the other end of said extractionzone a parainic naphtha fraction boiling in the range of 60 to 130 C.and having a density of less than 0.8, passing said aqueous solution andsaid naphtha fraction through said extraction zone in countercurrentrelation, and recovering the phenols princpally in the aqueous solutionand the thiophenols principally in the naphtha fraction.

6. A method of separating thiophenols from a mixture of phenols andthiophenols that is substantially free of neutral oils which comprisesthe steps of feeding said mixture of phenols to an extraction zone,feeding to one end of said extraction zone an aqueous solutioncontaining from about 50 to about 80 percent by weight of ethyleneglycol monoethyl ether, feeding to the other end of said extraction zonea paranic naphtha fraction boiling in the range of 60 to 130 and havinga density of less than 0.8, passing said aqueous solution and saidnaphtha fraction through said extraction zone in countercurrentrelation, and recovering the phenols principally in the aqueous solutionand the thiophenols principally in the naphtha fraction.

7. A method of separating thiophenols from a mixture of phenols andthiophenols that is substantially free of neutral oils which comprisesthe steps of feeding said mixture of phenols to an extraction zone,feeding to one end of said extraction Zone an aqueous solutioncontaining from about 50 to about 80 percent by weight of triethyleneglycol, feeding to the other end of said extraction zone a parainicnaphtha boiling in the range of 60 to 130 C. and having a density ofless than 0.8, passing said aqueous solution and said naphtha fractionthrough said extraction zone in countercurrentvrelation, and recoveringthe phenols principally in the aqueous solution and the thiophenolsprincipally in the naphtha fraction.

8. A method of separating thiophenols from a mixture of phenols andthiophenols that is substantially freeV of neutral oils which comprisesthe steps of feeding Vsaid mixture of phenols lto an extraction zone,feeding to one end of said extraction zone an aqueous solutioncontaining from about 50 to about 80 percent by Weight of dipropyleneglycol, feeding to the other end of said extraction zone a paraiinicnaphtha boiling in the range of to C. and having a density of less than0.8, passing said aqueous solution and said naphtha fraction throughsaid extraction zone in countercurrent relation, and recovering thephenols principally in the aqueous solution and the thiophenolsprincipally in the naphtha fraction.

9. A method of separating thiophenols from a mixture of phenols andthiophenols that is substantially free of neutral oils which comprisesthe steps of feeding said mixture of phenols to an extraction zone,feeding to one end of said extraction zone an aqueous solutioncontaining from about 50 to about 80 percent by weight of polyethyleneglycol, feeding to the other end of said extraction zone a paraffinicnaphtha boiling in the range of 60 to 130 C. and having a density ofless than 0.8, passing said aqueous solution and said naphtha fractionthrough said extraction zone in countercurrent relation, and recoveringthe phenols principally in the aqueous solution and the thiophenolsprincipally in the naphtha fraction.

References Cited in the ile of this patent UNITED STATES PATENTS2,218,139 Thomas et al. Oct. 15, 1940 2,556,213 Pieroni et a1. June 12,1 2,666,796 Gerin et al. Jan. 19, 1954

1. A METHOD OF SEPARATING THIOPHENOLS FROM A MIXTURE OF PHENOLS ANDTHIOPHENOLS THAT IS SUBSTANTIALLY FREE OF NEUTRAL OILS WHICH COMPRISESTHE STEPS OF FEEDING SAID MIXTURE OF PHENOLS TO AN EXTRACTION ZONE,FEEDING TO ONE END OF SAID EXTRACTION ZONE AN AQUEOUS SOLUTIONCONTAINING FROM ABOUT 50 TO ABOUT 80 PERCENT BY WEIGHT OF AN OXYGENATIONHYDROCARBON HAVING THE FORMULA